Final Site Information Package for National Remedy Review Board ...

6. Summary of Risks
The Bunker Hill Superfund Site was listed on the NPL in 1983 based upon high levels of
lead, arsenic, cadmium, and zinc in the local environment and high blood lead levels in
children living in communities near the smelter complex and related mining activities. In
the 1970s lead poisoning was widespread, with 75 percent of children exceeding a blood
lead level of 40 micrograms per deciliter (µg/dL). The health response has been ongoing for
decades, and now area children have blood lead levels close to the national average.
Historical mining wastes have created a legacy of pervasive elevated metals concentrations
that present significant measureable risks to many animals and plants throughout the Basin.
The risks are neither hypothetical nor potential future risks—the risks continue to exist
today.
Public health studies and epidemiologic and environmental investigations begun in the
1970s concluded that atmospheric emissions of particulate lead from the active smelter were
the primary sources of elevated blood lead levels in local children from the populated areas
of the Bunker Hill Superfund Site, later known as OU 1 of the Bunker Hill Box. Associated
risks to human health were evaluated through the 1990 Risk Assessment Data Evaluation
Report for the populated areas (OU 1) (“the RADER,” USEPA, 1990) and in the 1992 Human
Health Risk Assessment (HHRA) for the non-populated areas (OU 2) (SAIC, 1992). The
RADER evaluated both carcinogenic and noncarcinogenic effects of contaminant exposures.
The non-populated areas HHRA evaluated exposures either as baseline (resulting from
activities common to all members of the resident population) or as incremental (resulting
from potentially high-risk activities by some members of the local population or visitors to
the area).
Human health risks were further evaluated in the HHRA for the Coeur d’Alene Basin in
2001 (Idaho Department of Health and Welfare [IDHW], 2001). The results of this HHRA
were summarized in the 2001 NRRB Presentation Information (USEPA, 2001b; see
Supplemental CD, File B2-1). Subsequently, the ROD for OU 3 (USEPA, 2002) summarized
the results of a baseline HHRA of the Harrison to Mullan portion of the Upper Basin
(exclusive of the Bunker Hill Box, which was addressed in prior OU 1-specific risk
assessment reports), which includes all of the Upper Basin study area. An EcoRA (CH2M
HILL and URS Greiner, 2001) was prepared as part of the RI/FS for the Coeur d’Alene
Basin. The EcoRA characterized risks to aquatic and terrestrial organisms exposed to
hazardous substances associated with mining activities. A focused EcoRA was completed in
2006 to evaluate the effects of lead-contaminated soil on groundfeeding songbirds in the
riparian area of the Basin (CH2M HILL, 2006b).
As reported in CERCLA Five-Year Review Reports prepared for the Bunker Hill Superfund
Site (USEPA, 2000a, 2000c, and 2005), selected human health remedies that have been
implemented within the Upper Basin communities to date are protective, and they are
functioning as designed. However, elevated concentrations of mining-related metals in
surface water, soil, sediments, and biotic tissues continue to pose risks to people and to the
survival and growth of animal and plant species. The Five-Year Review Reports concluded
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